The invention relates to C-arm X-ray systems, and more particularly to a C-arm X-ray system with full volume imaging capability for use in interventional procedures.
Various C-arm X-ray devices and system are known in the art. For example, German patent No. DE 198 39 825 C1 (xe2x80x9cthe ""825 patentxe2x80x9d), incorporated herein by reference, discloses an X-ray device in FIG. 1A comprising circular support equipment 1. The circular support equipment includes a C-shaped arm or first ring segment 4. The first ring segment 4 is attached to the circular support equipment 1 via a first bearing equipment 9 and further includes an X-ray source 2 and an X-ray detector 3 disposed at opposing sides of a patient 7. The X-ray device of the ""825 patent also includes a second ring segment 5 attached to second bearing equipment 12 and head lining rail 13.
The circular support equipment 1, first bearing equipment 9, first ring segment 4, X-ray source 2 and detector 3 of the ""825 patent device may be used to perform conventional fluoroscopy. The second ring segment 5 may be pivoted about a tangential pivot axis to bring the second ring segment 5 into alignment with the first ring segment 4. This allows (when attached and aligned) 360 degree rotation of the X-ray source 2 and detector 3 about the patient 7. Hence, the ""825 patent devices include an ability to operate as a computer tomography device as well as a conventional C-arm type fluoroscope.
The ""825 patent device has its limitations, however. In particular, the second ring segment 5 must be mechanically aligned, brought into contact with, and plugged into (attached to) the first ring segment 4 before the CT mode of operation may be implemented. This requires that a mechanical tenon 28 which fits into a mortise 29 constructed within the second ring segment 5, as shown in FIG. 1A.
A bolt 30 is inserted into a bolthole of at least one mechanical tenon 28 in order to lock the first and second ring segments. As such, making the connection requires substantial effort in both the alignment and the locking together of the ring segments.
Moreover, the head lining 13, the second bearing equipment 12 and berth the equipment 6 take up a substantial volume which is certainly a hindrance to the technical individuals who would utilize the construction to perform both conventional fluoroscopic and CT scanning during an interventional medical procedure. The patient 7 is difficult to access in particular positions because of the structure itself, and the necessary elements required to lock the first and second ring segments.
The ""825 patent also includes two additional proposals for realizing the closed circle (ring) with its inherent ability to rotate a full 360 degrees. That is, the ""825 patent also includes an embodiment which uses two (2) interleaved c-shaped arcs (FIGS. 5-11).
Another embodiment of the ""825 patent is constructed to use two (2) c-shaped arcs connected vertically utilizing a hinge.
Each of the above-mentioned embodiments (i.e., the three (3)-introduced approaches) aim for the generation of a rigid circle or ring that can be used for performing 360xc2x0 rotations. The basic idea is to use the standard support of the C (16 in FIG. 1 of the ""825 patent) and simply increase the range of the rotation of the c-shaped connection between tube and detector (4, FIG. 1 of the ""825 patent) from 180 (FIG. 1) to 360xc2x0 (FIGS. 2, 7, 10, 11, and 14).
The tube and detector are supported either on two sides (FIG. 2) or on a single side only (rest). Where the first embodiment of the ""825 patent is limited to rotation of the tube-detector-ensemble around the patient axis (table axis), the second and third embodiments mentioned above basically provide a full 360 degrees of freedom (of course within the limitations given by the patient). That is, by allowing a choice of allowing the rotation axis to rotate the support of the closed circle or ring (16) around the horizontal rotation axis (10) or even the vertical rotation axis (11) allow for 360 degrees of freedom.
Where the first-mentioned embodiment requires additional space-consuming equipment (5, 14, 13, 15), solutions 2 and 3 (at least to a certain extent) do not require significant additional equipment. Hence, in fluoroscopic mode, the systems are almost equal to a fluoroscopic-only system from an applicational (functional) point of view. The major drawback of all solutions suggested taught by the ""825 patent is the need for rebuilding the system when switching between fluoroscopic and CT mode, and vice versa.
Accordingly, it would be desirable for those skilled in the art to realize a C-arm type X-ray system in which a second C-arm element is available for closing the gap in the primary or support C-arm to form a closed ring which overcomes the shortcomings of prior art C-arm X-ray systems, e.g., the ""825 patent.
It is therefore an object of the present invention to provide a C-arm X-ray system which supports full volume imaging capabilities with the full flexibility required for interventional procedures without a need to rebuild the system when switching between fluoroscopic and CT modes of operation.
It is another object of the invention to provide a C-arm X-ray system in which an inner xe2x80x9cCxe2x80x9d of a C-arm mechanism may be enabled and guided by an outer xe2x80x9cCxe2x80x9d to allow for 360 degree rotation of oppositely disposed X-ray source and X-ray detector mounted on the inner C-arm of the C-arm mechanism. The construction allows operation without the need for a conventional rigid C-arm support, such as that described in the prior art ""825 patent.
It must be noted that the inner xe2x80x9cCxe2x80x9d is never fixed to the support xe2x80x9cCxe2x80x9d, even when at rest. The use of the terms xe2x80x9cstablexe2x80x9d, xe2x80x9cclosed ringxe2x80x9d etc. are not meant to imply that the inner C-arm is affixed to the support C-arm. That is, the two xe2x80x9cC""sxe2x80x9d themselves possess the possibility to perform a 360xc2x0 rotation without the need to construct an auxiliary closed ring beforehand.
It is another object of the invention to provide a C-arm X-ray system that can provide a simple and elegant method of obtaining X-ray projections of a patient from any direction without having to move the patient.
It is another object of the invention to provide a C-arm X-ray system that can provide a simple and elegant method of switching between CT and fluoroscopic applications (e.g., angiographic), without moving the patient from one device to another.
It is another object of the invention to provide a C-arm X-ray system which provides a simple and elegant method of switching between CT and fluoroscopic applications (e.g., angiographic), while maintaining the patient in a common frame of reference (coordinate system) relative to a gantry (comprising the system). Consequently, acquisition of data from both applications allows the combined data to realize additional, previously unavailable diagnostic information, as well as easy patient access during an interventional procedure.
It is another object of the invention to provide a C-arm X-ray system in which a first support C-arm (e.g., 210 degree arc length) including an inner C-arm (e.g., at least 150 degrees of arc length) which inner C-arm may be automatically extended to close the gap in the support c-arm and allow an x-ray source and oppositely disposed x-ray receiver to rotate a full 360 degrees.
The arc length of the support xe2x80x9cCxe2x80x9d determines the size of the gap size (360xc2x0-arc length of support xe2x80x9cCxe2x80x9d) and hence the patient accessibility. It must be 180xc2x0 plus xc2xd overlap with the inner xe2x80x9cCxe2x80x9d. The inner xe2x80x9cCxe2x80x9d must have at least 180xc2x0, at most the same arc length as the support xe2x80x9cCxe2x80x9d, else the gap size would decrease. In order to make the construction as rigid and stable as possible, the inner xe2x80x9cCxe2x80x9d should have its maximum arc length. Both arc lengths should be the same and a compromise has to be made between stability and patient accessibility. A preferred embodiment may be constructed to be about a 210xc2x0 arc length for a 150xc2x0 gap size.
It is another object of the invention to provide a C-arm X-ray system in which a second C-arm element, constructed within a first support C-arm, may extend from a support mechanism within the first C-arm (at a first end) to close the gap and re-enter an opposite (second) end of the first C-arm.
It is another object of the invention to provide a C-arm X-ray system in which the xe2x80x9cCxe2x80x9d may be extended a full 360 degrees by including and inner C-arm element which may exit/enter each opposite C-arm support by use of a particular type of driving mechanism located at each end thereon, providing an ability to utilize both CT and fluoroscopic modes of system operation without the need to rebuild the system of move the patient under examination.
It is another object of the invention to provide a C-arm X-ray system in which an inner C-arm disposed within a support C-arm may be extended a full 360 degrees (circle) from within the support C-arm with a gear rim on its outer or inner surface, the gear ring providing a means to transfer rotation of diametrically opposed X-ray source and detector mounted on the closed ring.